<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .box {
            width: 448px;
            height: 252px;
            margin: auto;
            position: relative;
        }

        .hidden {
            width: 448px;
            height: 252px;
            background-color: rgba(99, 99, 99, 0.5);
            position: absolute;
            left: 0;
            top: 0;
            display: none;
        }

        .hidden img {
            position: absolute;
            top: 50%;
            left: 50%;
            margin: -17px 0 0 -17px;
            cursor: pointer;
        }

        .box:hover .hidden {
            display: block;
        }
    </style>
</head>

<body>
    <div class="box">
        <img src="img/tudou.jpg" alt="">
        <div class="hidden">
            <img src="img/arr.png" alt="">
        </div>

    </div>
</body>

</html>